What size is the oil pan bolt on a 2000 Chevy lumina?

There isn't a single size for all the oil pan bolts on a 2000 Chevy Lumina. The oil pan typically uses multiple sizes of bolts. You'll need to remove one and measure it with a bolt gauge or compare it to a known size. It's best to check your owner's manual or a repair manual specific to your vehicle's engine (3.1L V6 or 3.8L V6 were common in the 2000 Lumina) for the correct bolt sizes and torque specifications. Using the wrong size or tightening to the incorrect torque can damage the oil pan.